In the ground squirrel there are three anatomically distinct types of OFF-bipolar cells, which each using a different type of AMPA or kainate receptor to receive cone signals. Due to differences in receptor kinetics, each OFF-bipolar cell type carries a different temporal signal to inner retina. The different glutamate receptors also offer the possibility for distinct actions of modulators such as dopamine. Specific aims 1 and 2 test whether dopamine modulates transmission at the cone to OFF-bipolar cell synapse, whether modulation differs among OFF-bipolar cell types, and what type of intracellular cascades are involved. Specific aim 3 tests whether modulation by dopamine has a functional role in slow contrast adaptation.